When quadrisulphuret of lime is treated with an alkaline carbonate, a reciprocal change takes place; the carbonic acid takes the lime, and the alkali the sulphur, leaving however 1 atom of sulphur with the carbonate which precipitates. Hence a sulphuretted carbonate of lime is obtained and a trisulphuret of the alkali. The sulphur burns off from the carbonate below a red heat and leaves 75 per cent. of carbonate of lime; this affords an excellent analysis of quadrisulphuret of lime as far as lime is the object. Thus 540 of the above 1.056 quadrisulphuret took 100 test carbonate of potash (1.25), and gave a precipitate of 29 grains, which burned blue and left 22 grains = 12 lime, and 10 acid; but if 540 ∶ 12 ∷ 100 ∶ 2.2, as above determined synthetically: moreover, 12 lime, 10 acid, and 7 sulphur, are as 24 lime, 20 acid, and 14 sulphur; the composition of an atom of sulphuretted carbonate of lime, which is analogous to the sulphuretted sulphite of lime, as found above. When quadrisulphuret of lime is treated with as much sulphuric acid as is sufficient for the lime, the sulphur is in part precipitated, but it is in union with the sulphate of lime, or at least they are not separable by mechanical means. This compound is sold in the shops under the name of precipitated sulphur. It is about one half sulphate of lime, and the other half sulphur. The nitric and muriatic acids precipitate the sulphur partially from quadrisulphuret, but the sulphur assumes a viscid form and exhales sulphuretted hydrogen, and the proportion of the elements of quadrisulphuret are not easily obtained by any of these acids.